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Laborers in the sugar cane fields of Central America are experiencing a rapid and unexplained form of kidney failure. Above: Harvesting sugar cane in Chichigalpa, Nicaragua.

Jason Beaubien / NPR

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Jason Beaubien / NPR

Laborers in the sugar cane fields of Central America are experiencing a rapid and unexplained form of kidney failure. Above: Harvesting sugar cane in Chichigalpa, Nicaragua.

Jason Beaubien / NPR

In 2014 and 2015, NPR reported a mysterious form of kidney disease that has killed thousands of thousands in Central America, many of them in their 30s and 40s. Now there's a new theory about a possible cause.

Dr. Cecilia Sorensen in an editorial in the current issue of The New England Journal of Medicine: "A sentinel disease" in the Era of Climate Change.

Goats are curious animals and "Goats and soda" is a curious blog. Over the next week, we'll look back on some of our favorite stories to see "[…]" (19659013) "It's an exacerbates cardiovascular disease." respiratory disease, "says Sorensen, an emergency medicine physician who also teaches at the University of Colorado School of Medicine.

Shaper sugar cane cutter Manuel Antonio Tejarino was photographed in March 2014. He died of kidney disease two months later.

Jason Beaubien / NPR

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Jason Beaubien / NPR

Former sugar cane cutter Manuel Antonio Tejarino was photographed in March 2014. He died of kidney disease two months later.

Jason Beaubien / NPR

The disease, which has become the second-leading cause of death in Nicaragua and El Salvador, was first reported in the 1990s. It was a strange new type of kidney failure. Sugar cane cutters from plantations in Nicaragua, El Salvador and Guatemala were turning up at clinics with end-stage kidney disease. Just had a few years before. These workers did not have any diabetes or hypertension.

Among the early cases, almost all the patients did not work on the low-lying plains near the Pacific Coast. Later the condition thus found among other people in the area, including miners, fishermen and workers in hot industrial plants. CKDu in Central America were relatively young farm laborers.

"Then we started realizing, wait a sec, there's a very similar disease process that's described in India and Sri Lanka," Sorensen says.

"Because it looks almost identical," says Sorensen. And there's been reports on it happening in Africa as well as in the Middle East. "

Adding to the difficulty of unraveling this mystery, CKDu appears to hit poor people in poor countries with poor health care systems. Sorensen says.

Sorensen wondered if this disease could happen, it might not even know that's because there is no one's looking for it. But that's not easy to determine. "

" It's very difficult to prove direct attribution and say this is because of climate change, "she says.

Climate change is just one of the theories behind what's causing CKDu. Most focus on heat stress and dehydration. Others propose a link to drinking water, possibly with heavy metals or agricultural chemicals. Sri Lanka banned the herbicidal glyphosate, sold under the brand name Roundup, about CKDu. Nicaragua blamed the epidemic on home-brewed alcohol.

Sorensen says there's probably not one single cause. In her words it's most likely "multi-factorial."

Neil Pearce, a professor of epidemiology at the London School of Hygiene and Tropical Medicine, has also said: "This is a hot and muggy – and getting hotter." been studying CKDu for years.

"It's a very unusual phenomenon. I've done this work in this general area for 40 years, and it's very unusual to come across something like this," he says.

"Pearce has been tracking sugar cane workers in Nicaragua and found that over a two-year period some of them had lost their third function."

"It may well "But due to heat stress and the extremely bad working conditions in Central America."

He does not think that the short-term climate is over last few decades would cause a significant shift in people's health.

Pearce has also been looking for CKDu in other places with similar climatic conditions to Central America's Pacific Coast Plains – Northern Peru and Malawi , for example – and has not found it.

They are both. They are both close to each other, and some of them are not equally hot, and they're not the hottest parts of India, "he says. "Yes, there's something very strange going on. It's quite interesting scientifically and obviously tragic in terms of the death and illness that it's caused."

Sorensen in her editorial does not claim to have the exact answer to what's causing CKDu. It's about to be hard physical laboratory in intense tropical heat. The climate change may be "mysterious" new ailments.